1) The fusion of hardcore punk and thrash metal sounding exactly like the sound of it - Integrity or Converge are good examples

2) Extreme metal, usually simplified, with emo clean singing, screamo harsh vocals and an excess of breakdowns which sound nothing like hardcore punk. A fabricated genre aimed at making money and being popular. Why is this called "metalcore" is beyond me.

1) Integrity is a metalcore band and you know why when you listen to it. It takes thrash metal riffs and uses them on hardcore punk drum patterns or vice versa. You know where the "metal" part and the "-core" part came from.

2) Atreyu is a metalcore band. They sound more like nu-metal with chuggy breakdowns. However nobody took his time to understand what exactly the hardcore influences of theirs are - I can certainly hear no breakdowns in my hardcore punk

A blend of hardcore and metal music that evolved in the mid-to-late 90's with bands like Unbroken, Earth Crisis, Harvest, Endeavor, Poison The Well and Unearth. There is a liberal use of breakdowns in the music and the lyrical themes range from the political to the personal.

Metalcore is a genre that has been around since the eighties but not totally popularized until the mid 90's with bands such as Unearth, the modern forerunners in the genre. It includes a mixture of hardcore punk and heavy metal and uses generally two guitarists, a bassist and double kick drums for the instrumentals. Many bands use more than one singer, one generally for more melodic lines and the other, lead singer, who carries many of the vocal burden and usually "screams".

A genre of music that had began in the late 80s/early 90s. Originally combining elements of metal and hardcore, it has now evolved into a dime-a-dozen plethora of bands that sound exactly the same. New school metalcore bands borrow heavily from melodic European death metal combined with stolen Slayer riffs and vocals ranging from annoying screams to cupped-mike growls. Band names are usually longer than the songtitles (i.e. Between The Buried And Me, Every Time I Die, etc). Mostly caters to mallrat teens who are glued to Facebook, shop at Hot Topic, wear skinny jeans, skateboard, and play Call Of Duty all day long.

Old school metalcore: Insult II Injury, Merauder, Into Another

New school metalcore: Bullet For My Valentine, As I Lay Dying, All That Remains

A genre of new age metal that began in the late 1990's with bands like Slipknot and Killswitch Engaged. It infuses Punk and Extreme Metal to create a strong, yet complex rhythm. It differs from Punk Metal by putting emphasis on the breakdown portion of the song, and often invoke a more depressed and somewhat hopeless feeling. Some other modern examples include Attack Attack, Underoath, Atreyu, Trivium, All That Remains, and many more.

A subgenre of metal and hardcore that is kind of like communism. If it were to be done correctly, it would be perfect, but hardly anyone can do it right and therefore it is mainly horrible. There are some metalcore bands that I actually enjoy (The Dillinger Escape Plan, Hatebreed, Every Time I Die), but most of it (and certainly the most popular bands) incorporate pop punk, electronic, glam, crunk, and all sorts of other shit and make it sound worse than putting a cat in a blender. Not to mention deathcore, which is just an attempt to make an anti-metalcore genre, is even worse and brings shame to death metal. Another thing that humor's me with most metalcore is the bands claim to be the brutalist shit alive but they dress like a 12 year old scene girl.

Good metalcore: Every Time I Die, TDEP, Hatebreed, All That Remains (sort of), ect.
Bad metalcore: Bring me the Horizon, Of Mice and Men, Asking Alexandria, The Black Dahlia Murder, Chelsea Grin, ect.

A watered-down form of melodic death metal, due to it's lack of keyboard, less brutal vocals, and overall shorter songs. Listened to by scenester kids, along with deathcore, who are ignorant to it's superior predecessor which originated in Sweden.